1. Field of the Invention
The present invention relates to a joint, especially relates to a joint having a crossing part where two channels cross.
2. Description of the Related Art
Heretofore, a high pressure joint such as an elbow joint, a T-connection and a cruciform joint is a member which is provided with a crossing part where two channels cross and which supplies high-pressure fluid to a desired location, bending the high-pressure fluid supplied from a high pressure pump, joining it and branching it respectively in the crossing part, and the high pressure joint is widely used in various high-pressure fluid injection systems. As in the crossing part in the high pressure joint, pressure (internal pressure) by high-pressure fluid flowing in the channel repeatedly acts and varies, it is known that a crack caused by the internal pressure has an important effect upon the life of the joint (for example, refer to Japanese Unexamined Patent Application Publication No. 2008-510937 (claim 1, claim 2, Paragraphs 0018 to 0020, FIGS. 7, 8A, 8B, 8C, and 13)).
A high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937 makes compressive energizing force concentrate over and under a location (a crossing part) where a channel 128 in a direction of the X-axis and a channel 130 in a direction of the Y-axis respectively formed on a common plane (an XY plane) in a main body 122 cross and negates separating power (internal stress) in a direction of the Z-axis which acts perpendicularly to the common plane and which tries to separate in the direction of the Z-axis by the compressive energizing force so as to prevent a crack caused on the common plane (the XY plane).
Concretely, the high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937 clamps first and second compressive members 132 in which a compressive protrusion 134 that applies compressive force with the main body 122 between is formed by a clamp 138 and applies compressive energizing force to the crossing part.
However, first, as a position of the compressive protrusion 134 and a position of the clamp that applies compressive force are different in the high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937, the high pressure joint has a problem that a position, a direction and the magnitude of compressive force applied to the crossing part where the channels cross cannot necessarily be properly set.
Besides, secondly, as various internal pressure acts on the crossing part where the channels cross by high-pressure fluid, the high pressure joint has a problem that unexpected various deformation occurs in the crossing part by compressive force (uniaxial lateral compression) when the compressive force in the direction of the z-axis is applied to the center of the crossing part as in the high pressure joint disclosed in Japanese Unexamined Patent Application Publication No. 2008-510937, internal stress newly caused by the deformation is superimposed on internal pressure of the high-pressure fluid and new damage may be caused. It is also an indeterminate factor that a direction and a position of compressive force applied to the crossing part are not necessarily properly managed.
Unexpected various internal stress (for example, internal stress in a direction along the XY plane) newly caused by compressive force applied to the center of the crossing part will be described, referring to FIGS. 1, 2A, 2B, 2C, 3A, 3B and 3C below.
Referred FIG. 1 is a perspective view showing internal pressure that acts on the crossing part where the channel in the direction of the X-axis and the channel in the direction of the Y-axis cross. FIGS. 2A, 2B, 2C are drawings for explaining internal stress by the internal pressure that acts on the crossing part, wherein FIG. 2A is a front view viewed from the direction of the X-axis, FIG. 2B is a side view viewed from the direction of the Y-axis, and FIG. 2C is a plan view viewed from the direction of the Z-axis and showing a state in which a crack occurs on the XY plane. FIGS. 3A, 3B, 3C show relation between the internal stress by the internal pressure and compressive force, wherein FIG. 3A is a front view viewed from the direction of the X-axis, FIG. 3B is a side view viewed from the direction of the Y-axis, and FIG. 3C is a front view showing a state in which internal stress in the direction along the XY plane is caused by compressive force P.
In the following description, as shown in FIG. 1, for the convenience of the description, a virtual plane on which a first channel 110 and a second channel 120 pass is called an XY plane, a direction of the first channel 110 is called a direction of the X-axis, a direction of the second channel 120 is called a direction of the Y-axis, and a direction perpendicular to the XY plane is called a direction of the Z-axis. Besides, a plane including the Y-axis and the Z-axis is called a YZ plane and a plane including the X-axis and the Z-axis is called an XZ plane.
<Internal Stress by Internal Pressure>
As shown in FIG. 1, in a cruciform joint 100, the first channel 110 in the direction of the X-axis and the second channel 120 in the direction of the Y-axis respectively formed in a casing 100a join in a crossing part 130 on the XY plane. An intersection 140 in the crossing part 130 is an interface on the XY plane of a peripheral wall 110a of the first channel 110 and a peripheral wall 120a of the second channel 120 (see FIG. 2C). That is, the intersection 140 is an intersection of the peripheral wall 110a of the first channel 110 and the peripheral wall 120a of the second channel 120 when the crossing part 130 is viewed from the direction of the Z-axis as shown in FIG. 2C.
At this intersection 140, as shown in FIG. 2A, internal stress Q1 by internal pressure q1 of pressure fluid flowing in the first channel 110 acts in the direction of the Z-axis. Besides, as shown in FIG. 2B, internal stress Q2 by internal pressure q2 of pressure fluid flowing in the second channel 120 acts in the direction of the Z-axis. Therefore, stress concentration occurs at the intersection 140 by the internal stress Q1 and the internal stress Q2, a crack CR1 is apt to be caused, and as shown in FIG. 2C, the crack CR1 extends on the XY plane.
To prevent the crack CR1 caused on the XY plane, as shown in FIG. 1, the internal stress Q1 and the internal stress Q2 are negated by compressive force P (P1, P2)(see FIGS. 2A, 2B) by pressing the casing 100a so that the compressive force P (P1, P2) is applied to the center 150 (see FIG. 2C) of the crossing part 130 from both sides in the direction of the Z-axis as shown in FIG. 1, and the occurrence of the crack CR1 (see FIG. 2C) can be inhibited.
Concretely, as shown in FIG. 3A, the internal stress Q1 by the internal pressure q1 of the pressure fluid flowing the first channel 110 is negated by the compressive force P (P1) and as shown in FIG. 3B, the internal stress Q2 by the internal pressure q2 of the pressure fluid flowing in the second channel 120 is negated by the compressive force P (P2).
For the convenience of description, the compressive force P is conceptually assorted into the compressive force P1 and the compressive force P2 to correlate with the internal stress Q1 and the internal stress Q2, however, the compressive force P may be also considered resultant force of the compressive force P1 and the compressive force P2.
<New Internal Stress by Applied Compressive Force>
However, it is supposed that new various internal stress by unexpected deformation occurs in the crossing part 130 by applying the compressive force P to the center 150 of the crossing part 130 from the direction of the Z-axis.
For example, as shown in FIG. 3C, in view of an intersection 160 (see FIG. 1) on the YZ plane (a plane including the Y-axis and the Z-axis and perpendicular to the X-axis) where the peripheral wall 110a of the first channel 110 and the peripheral wall 120a of the second channel 120 cross, internal stress Q4 in the direction of the X-axis perpendicular to the YZ plane occurs because deformation that a diameter of the second channel 120 is extended in the direction of the X-axis and the diameter is reduced in the direction of the Z-axis occurs (see a reference sign E) by applying the compressive force P.
Further, at the intersection 160 (see FIG. 1) on the YZ plane, as internal stress Q3 by the internal pressure q2 of the pressure fluid flowing in the second channel 120 acts in the direction of the X-axis, resultant force of the internal stress Q4 by the compressive force P and the internal stress Q3 in the direction of the X-axis by the internal pressure q2 of the pressure fluid causes a crack CR2 in a direction along the YZ plane.
Accordingly, a new harmful effect by the internal stress Q4 in the direction of the X-axis perpendicular to the YZ plane which is caused by the compressive force P in the direction of the Z-axis applied to the center 150 (see FIGS. 1, 2C) of the crossing part 130 where the plural first channel 110 and second channel 120 cross is required to be inhibited.
The present invention is made in view of such a background and provides a joint in which a position, a direction and the magnitude of compressive force applied to a crossing part where two channels cross are properly set, the occurrence of new internal stress by compressive force that pressurizes the crossing part is inhibited and the durability can be enhanced.